1. Field of the Invention
The invention relates to optical storage devices, and more particularly, to a method and an apparatus of adjusting a sampling phase of the disc signal.
2. Description of the Prior Art
In communication systems, the transmitter utilizes a synchronization pattern in order to align each frame and transfer data. The receiver searches the synchronization pattern when receiving signals and to decode data following after the synchronization pattern. For example, the synchronization pattern of a digital versatile disc (DVD) is a series of 14 signals, whose logic level are all 1. When decoding the DVD signals, the DVD displayer continuously compares the DVD signals with the 14 logic-level-1 signals to search for the synchronization pattern in the DVD signals and decode the following data after the synchronous pattern.
In communication systems, the receiver utilizes a sampling clock to sample the analog signal, and utilizes a signal level to transform the sampling clock into a digital signal for following digital signal process. However, signal jitter causes the sampling signal not to sample the analog signal according to an ideal timing so that the sampling value of the sampling signal diverges from the ideal value. That is, the bit error rate of the communication system rises. When the signal jitter drives the sampling clock to sample at an incorrect timing (that is, the phase of the sampling clock shifts), the sampling signal is determined as an incorrect signal level so that the synchronization signal of the disc signal is impacted or the following decoding procedure of the disc signal is impacted. Furthermore, the disc signal may not be decoded smoothly and correctly.